Method and apparatus for on-site mixing of liquid deicer

ABSTRACT

An apparatus and method for preparing and dispensing a liquid deicer. The apparatus and method allow deicer ingredients or precursors to be combined in an exothermic reaction to produce a heated deicer at the location where it will be used. In one implementation, potassium hydroxide and acetic acid are combined using the apparatus and method to make hot potassium acetate for use in numerous deicer applications, including deicing of airport runways.

RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/614,755 filed Dec. 21, 2006, entitled “Method and Apparatus forOn-Site Mixing of a Liquid Deicer”, which is a divisional of U.S. patentapplication Ser. No. 10/302,759 filed Nov. 22, 2002, entitled “Methodand Apparatus for On-Site Mixing of Liquid Deicer,” which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention is directed to apparatuses and methods for makingdeicing compositions, as well as to deicer compositions made use theapparatuses or methods. In particular, the invention is directed toapparatuses and methods for making heated deicing compositions on-siteat locations where the deicer will be applied, and to such heateddeicing compositions.

BACKGROUND OF THE INVENTION

Liquid deicer compositions are used for many applications, such asdeicing roadways, bridges, machinery, airport runways, and aircraft. Oneof the most important criteria for some deicers, in particular thoseused in airport applications, is that they be non-corrosive because theyare used near corrosion sensitive equipment. Today, modem airports intemperate climates usually have deicing programs in place that carefullydeice runways. These deicing programs use liquid deicers applied atambient temperatures, often at or below the freezing temperature ofwater. Although these deicing systems are in place at most modemairports, a need remains for improved deicing equipment and deicers. Inparticular, a need remains for deicing equipment and methods thatimproves on existing equipment and methods.

SUMMARY OF THE INVENTION

The present invention is directed to an apparatus and method for forminga heated liquid deicer. In one implementation of the invention theapparatus includes two vessels configured and arranged for retainingdeicer precursors: one vessel with an acidic liquid and one with analkaline liquid. These liquids, when combined, undergo an exotherrnicreaction to produce a heated liquid deicer. For example, acetic acid andpotassium hydroxide can be mixed to produce heated potassium acetate,which is an effective liquid deicer.

The apparatus generally includes a mixing vessel configured and arrangedfor the mixing and exothermic reacting of the acidic liquid and thealkaline liquid. The mixing vessel has an input for the acidic liquid,an input for the alkaline liquid, and an output for the heated reactionproduct of the acidic liquid and alkaline liquid. This heated reactionproduct is a heated liquid deicer. A liquid transfer mechanism incommunication with the first and second vessels is also provided, andthis mechanism is configured for the controlled transfer of the acidicliquid and the alkaline liquid into the mixing vessel.

The material formed using the apparatus and method is referred to hereinas a deicer composition. Generally, deicer compositions are used toremove ice from a surface. However, the composition made in accordancewith the invention is also suitable for use as an anti-icer that isapplied to a surface before ice forms on it. The apparatus and method ofthe invention can also be used to make a composition that is appliedbefore or after ice has formed. For the sake of simplicity, both suchuses of the composition are referred to herein as a “deicer”, unlessotherwise noted. Thus, deicers referred to within this description canbe used both to deice a surface or as an anti-icer for preventing iceformation. In addition, the composition can function as both a deicerand an anti-icer because it can be applied initially as a deicer, butremaining material then functions as an anti-icer after existing ice hasbeen removed.

The above summary of the present invention is not intended to describeeach 5 discussed embodiment of the present invention. This is thepurpose of the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully explained with reference to thefollowing drawings.

FIG. 1 is a simplified drawing of a vehicle on which a systemconstructed and arranged in accordance with the invention has beeninstalled.

FIG. 2A is a general schematic diagram of a system constructed andarranged in accordance with a first implementation of the invention.

FIG. 2B is a general schematic diagram of a system constructed andarranged in accordance with a second implementation of the invention.

FIG. 3A is a simplified drawing of a first mixing vessel constructed andarranged in accordance with the invention.

FIG. 3B is a simplified drawing of a second mixing vessel constructedand arranged in accordance with the invention.

FIG. 3C is a simplified drawing of a Third mixing vessel constructed andarranged in accordance with the invention.

FIG. 4A is a simplified drawing of a first mixing vessel constructed andarranged in accordance with the invention.

FIG. 4B is a simplified drawing of a second mixing vessel constructedand arranged in accordance with the invention.

FIG. 4C is a simplified drawing of a third mixing vessel constructed andarranged in accordance with the invention.

While principles of the invention are amenable to various modificationsand alternative forms, specifics thereof have been shown by way ofexample in the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit the invention tothe particular embodiments described. On the contrary, the intention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the disclosure and claims.

DESCRIPTION OF THE EMBODIMENTS

The present invention is directed to an apparatus and method forpreparing and dispensing a liquid deicer. The apparatus and method allowdeicer ingredients (also referred to as deicer precursors) to becombined in an exothermic reaction to produce a heated deicer. Thismixing reaction typically occurs at the location where the deicer willbe used. For example, potassium hydroxide and acetic acid can becombined using the apparatus and method to make hot potassium acetatefor use as a deicer, such as to deice runways at airports. The hotpotassium acetate functions primarily as a chemical deicer thatdepresses the freezing point of water, thereby causing ice to melt attemperatures below 0° C. However, the elevated temperature of the deicerprovides additional deicing effect.

In one implementation, the present invention includes a first vesselconfigured and arranged for retaining and dispensing an acidic liquidand a second vessel configured and arranged for holding and dispensingan alkaline liquid. A third vessel is configured and arranged for themixing and exothermic reacting of the acidic liquid and the alkalineliquid. This mixing vessel has an input for the acidic liquid, an inputfor the alkaline liquid, and an output for the heated reaction productof the acidic liquid and the alkaline liquid, this reaction productbeing a liquid deicer. In addition, the invention includes a liquidtransfer mechanism, such as one or more pumps, in communication with thefirst and second vessels. This liquid transfer mechanism is configuredfor the controlled transfer of the acidic liquid and the alkaline liquidinto the mixing vessel.

This system is shown generally in FIG. 1 and more specifically in FIG.2A. In FIG. 1, the system 10 is shown with a tank 12 containing a deicerprecursor (such as potassium hydroxide or acetic acid). This tank 12connects to a mixing vessel 14. Another tank, not shown, containing adifferent precursor would also connect to mixing vessel 14. The twoprecursors mix in chamber 14 and then travel on to an optional dispenser16 that generally includes at least one nozzle 18 used to spray thedeicer onto a surface or object that is to be deiced. In someimplementations the nozzle is at the end of a hose contained on a spool19, which provides greater flexibility in applying deicer to largeobjects or surfaces. In certain embodiments the heated deicer formedusing the system is pumped up a boom in order to be sprayed on elevatedobjects.

The various elements of this system are depicted schematically in FIG.2A. First vessel 20 is configured and arranged for retaining anddispensing an acidic liquid and second vessel 22 is configured andarranged for holding and dispensing an alkaline liquid. A third vessel24 is configured and arranged for the mixing and exothermic reacting ofthe acidic liquid and the alkaline liquid. This mixing vessel 24 isconnected by a liquid carrying line 26 (such as a hose or pipe) to thefirst vessel 20 and by liquid carrying line 28 (also a hose or pipe, forexample) to second vessel 22. A liquid transfer mechanism consisting ofpumps 30 and 32 is used to controllably move liquid deicer precursorsfrom the two vessels 20, 22 into the mixing vessel 24. This liquidtransfer mechanism is configured for the controlled transfer of theacidic liquid and the alkaline liquid into the mixing vessel 24. Afterbeing mixed, liquid deicer flows out of the mixing vessel and out anozzle 31 as spray 33. In the embodiment depicted in FIG. 2A this liquidmoves through a hose 34, but it will be appreciated that this hose isoptional and other ways of dispensing the liquid deicer are appropriate.

FIG. 2B shows an alternative embodiment of a system for creating aheated deicer. This system is similar to the one depicted in FIG. 2A,but contains one pump 27 rather than the two pumps 30, 32. Although thissystem has just one pump, the pump simultaneously pumps the two liquidswithout mixing them together. Not until the liquids reach the mixingvessel 24 do they come together to react and form the liquid deicer FIG,2B also shows an additional tank 36. This tank 36 contains a corrosioninhibitor that can be added to the deicer so that the deicer is lesscorrosive to surfaces and objects on which it is applied.

The two example apparatuses disclosed in FIGS. 2A and 2B represent twoacceptable implementations of how an apparatus can be constructed inaccordance with the invention. However, various changes, additions, andsubtractions can be made from the two depicted apparatuses. For example,various nozzle configurations are possible, and some implementations donot even use a nozzle. Also, various pressure release mechanisms may beadded to the mixing vessels, as well as control systems for regulatingthe mixing of the two deicer precursors. Thus, FIGS. 2A and 2B showexamples of how the present invention may be practiced, but are notlimiting in that regard.

One of the key elements of the present invention is the mixing vessel.The mixing vessel can be, and typically is, smaller than the primarychambers containing the unmixed acidic and alkaline liquids. The purposeof the mixing vessel is not to retain large volumes of mixed deicer, butrather to provide a temporary location in which the exothermic reactionbetween the two ingredients can occur, after which the resultant liquiddeicer is applied to a surface. In most implementations the mixingvessel or chamber is constructed to allow the highly exothermicacid-base reaction to progress to completion or nearly to completion. Itis important that this reaction proceed to completion or near completionbefore the deicer is dispensed because it is normally not desirable tohave non-reacted precursors discharged from the apparatus due to theircorrosive natures.

The mixing vessel is generally constructed in a fashion that allows itto withstand the high temperatures, and also to withstand steamgenerated during the exothermic reaction. Certain implementationsrequire the mixing vessel to withstand pressures developed by theexothermic reaction, while other implementations provide one or morevents or pressure release valves to release this pressure. One way ofhandling steam generated within the mixing vessel is to permit it toescape or venting through a release valve. Another way of handling thesteam is to use it to force the mixed deicer through an exit in themixing vessel. In this manner the steam and vapors can be used togenerate pressure. Alternatively, the steam can be partially vented andpartially used to force the mixed deicer through the exit.

As noted above, the mixing vessel should have a configuration thatallows for the acidic and alkaline liquids to be rapidly and safelymixed together. Numerous configurations are within the scope of thepresent invention, including elongate chambers, some of which can beformed of a long, relatively narrow pipe. In some implementations themixing vessel contains one or more static mixing vanes. Alternatively, astirring means can be used, such as a rotating prop or blade.

The invention covers numerous implementations in which different vesselconfigurations are used. The vessel can be as simple as the convergenceof two pipes carrying deicer precursors into a third pipe that willdischarge the deicer onto a surface, or can be relatively complex. In afirst embodiment, shown in FIG. 3A the vessel comprises a substantiallyenclosed chamber 40 that has inputs 42, 44 and an outlet 46. A releasevent 48 is also depicted, the release vent configured to permit theescape of excess pressure. When such pressure is released, it typicallyincludes the release of steam along with incidental amounts of liquids.However, in certain circumstances it is possible that larger amounts ofliquids will be released, in which case it is desirable that the liquidscomprise mixed deicer as opposed to precursor ingredients. When arelease vent is used it is preferable that the vented gas or liquids bedischarged away from where persons are likely to be positioned. Thus theoptional release vent is often positioned at the end of the chamber mostdistant from the input streams, thereby promoting the thorough reactionof any incidentally discharged materials.

An alternative embodiment is shown in FIG. 3B, where a plurality ofstatic fins 48 is positioned within chamber 40. The static fins 50promote the thorough mixing of the deicer precursors by stirring theprocurers together as they pass through the chamber. The heat (andsometimes steam) generated by the exothermic reaction of the precursorsalso helps to promote movement and stirring of the ingredients.

In many implementations of the invention the acid liquid and alkalineliquid are rapidly mixed together at one junction. However, in otherimplementations the reaction is attenuated by slowly mixing the twoliquids together. An example of how such gradual mixing can beaccomplished is shown in FIG. 3C, which has a chamber with a singleentrance for one liquid (either the acid or the alkaline liquid) plusmultiple entrances 54 for the other liquid. Thus, in someimplementations the apparatus includes a mixing vessel having multipleinputs for the. alkaline liquid. In other implementations the mixingvessel has multiple inputs for acid liquid. This gradual mixing approachis suitable for various implementations, particularly when one of theingredients is highly concentrated.

Additional implementations are shown in FIGS. 4A, 4B, and 4C, whichdepict long, narrow mixing chambers. Such chambers can be constructed,for example, from segments of stainless steel pipe. The chamber of FIG.4A is long and narrow, but without internal mixing vanes. Suchimplementations are suitable for circumstances where the length of thechamber is long enough to have thorough mixing merely by the turbulencegenerated within the chamber by movement of the liquids and by thewarming of the liquids as a result of the exothermic reaction. In FIG.4B a similar chamber 62 is depicted, but this chamber 62 also contains arotating stirrer 66 to promote mixing. FIG. 4C shows yet anotherimplementation with a chamber 64 having multiple mixing vanes 68. Thesemixing vanes 68 are constructed so as to stir the liquid as it passesthrough the chamber, thereby promoting reaction.

An alternative means for mixing the acid and alkali deicer precursors isby an impingement mechanism that directs streams of the precursorstogether so that that they adequately react. For example, two nozzlescan be placed adjacent to one another, one nozzle with an acid and onewith an alkali, and the streams from each nozzle are directed towardeach other to cause mixing of the precursors to form a heated deicer. Insuch implementations a vessel or chamber is not necessarily used to mixthem, although it is possible to impinge the two liquids within achamber to promote mixing.

As noted above, the invention typically includes a transfer mechanismfor moving the acid and alkaline liquids from their storage containersinto the mixing vessel or chamber. In general such transfer mechanismwill include one or more pumps. However, gravity fed systems can also beused, as can other systems that can move a regular, metered amount ofliquid from one tank into the other. The liquid transfer mechanism cancomprise a first pump connected to the first vessel and a second pumpconnected to the second vessel.

Various acidic liquids are useful with the invention, including, but notlimited to, hydrochloric acid, formic acid, adipic acid, sulfuric acid,maleic acid, acetic anhydride, maleic anhydride, propionic acid, lacticacid and acetic acid. One particularly desirable acidic liquid is aceticacid. Similarly, various alkaline liquids are useful with the invention,and include but are not limited to sodium hydroxide, calcium hydroxide,magnesium hydroxide, potassium hydroxide, ammonia, calcium oxide,magnesium oxide, calcium hydroxide, and annnonium hydroxide. Oneparticularly desirable alkaline liquid comprises potassium hydroxide.Normally from 25 to 75 percent concentrations of each reactant can beused, but concentrations of 100% such as glacial acid in someembodiments are contemplated.

The deicer produced using the present invention is typically a potassiumacetate solution made from the mixing of potassium hydroxide and aceticacid. Other deicers that can be produced include, but are not limitedto, ammonium acetate, ammonium formate, ammonium propionate, sodiumacetate, sodium formate, sodium propionate, potassium formate, potassiumpropionate, and potassium citrate.

In most implementations it is necessary that the acidic and alkalinematerials be combined in acid/base equivalents, which is typicallyequimolar quantities, to promote a complete reaction of both materials.An excess of either composition can result in an undesirably corrosivedeicer composition. The apparatus and method typically include one ormore aspects that promotes and ensures that proper amounts of eachprecursor liquid (the acid and alkali) are added in proper quantities.The primary manner in which such control is maintained is typically byhaving a transfer mechanism that accurately transfers the two (or more)precursors. Thus, when one or more pumps are used they should beaccurate and reliable. It is desirable in some implementations to have asingle pump mechanism transfer both the acidic liquid and the alkalineliquid, such as by having a single shaft drive two piston pumps, onecorresponding to each liquid. Having a single pump mechanism isadvantageous because it assures that the two liquids will be pumpedsimultaneously. This avoids inadvertent transfer of one liquid while theother liquid is not being transferred.

Another aspect of the invention can include a controller for regulatingthe transfer mechanism, the controller configured to regulate therelative flows of acidic liquid and basic liquid such that the reactionproduct leaving the mixing vessel has a substantially neutral pH.Alternatively, the controller can be configured to regulate the relativeflows of acidic liquid and basic liquid such that the reaction productleaving the mixing vessel has a pH substantially equal to the pH of asolution having the complete neutralization of the acidic and basicliquids. In yet another implementation the controller is configured toregulate the relative flows of acidic liquid and basic liquid such thatthe reaction product leaving the mixing vessel has a pH from about 4 toabout 11.

In some such implementations the apparatus includes a sensor 70 fordetermining the concentration of the alkaline liquid, the acidic liquid,or both. Also, in some implementations the apparatus includes a sensorand feed-back loop that shuts the system down when the mixing of theacid and alkali are not complete. For example, a pH feed-back loop maybe incorporated into certain implementations of the system. This pHfeedback loop measures the pH of the deicer as it exits the apparatus,and the system shuts down when the pH moves outside of desiredparameters.

The apparatus of the invention normally also contains at least onenozzle in liquid communication with the mixing vessel, the nozzleconfigured to discharge the heated reaction product of the acidic liquidand alkaline liquid. The nozzle may include just one hole, or caninclude a plurality of holes. In most implementations the reactionproduct is discharged under pressure through this nozzle or nozzles, andthe pressure is developed at least in part by the reaction of the acidicliquid and alkaline liquid.

In some implementations of the invention the deicer is formed from acombination of precursors plus premixed deicer. For example, the deicercan include the precursors that are mixed together and then added topre-mixed deicer. This implementation has the advantage of warming thepremixed deicer to a higher temperature, although typically not to thetemperature reached by using just the deicer precursor materials.

In certain implementations corrosion inhibitors are added to the deicerin order to prevent corrosion of objects that are being deiced (such asairport runways) and surrounding objects in the environment (such asiron reinforcements in the concrete). Numerous suitable corrosioninhibitors are appropriate for use with the present invention, andinclude phosphates, amines, nitrates, and silicates. These corrosioninhibitors can be used individually or in combination with one another.The inhibitors can be pre-added to the vessel containing the acidicliquid, pre-added to the vessel containing the alkaline liquid, or both.Alternatively, the corrosion inhibitor may be added to the acid/basemixture from a tank containing the corrosion inhibitor by means of ametering pump.

It is typically important to control the amount of each of the liquidsbeing mixed. Such controls can be accomplished by having a static systemthat mixes preset amounts of the liquids together based upon theiroriginal concentration. Alternatively, sensors can be placed in theinput flow streams, the output stream, or both to measure theconcentration of incoming materials and outgoing materials to assurethat a proper mixture is obtained. Sensors providing feedback withregard to the mechanical, electrical, thermal, pH, conductivity or otherproperties of the liquid precursors or the mixed deicer can be included.These sensors function with the control system to ensure that adequateamounts of precursors are safely mixed together properly and fully tomake a suitable deicer.

This deicing system can also be used on bridges or any paved surfacethat requires deicing. Typically this deicing system is used on a mobilebasis, but can also be a stationary system.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description.

1. A method of deicing a surface, comprising: mixing, in a vessel, afirst deicer precursor and a second deicer precursor to create a deicermixture; responsive to the mixing of the first and second deicerprecursors, permitting an exothermic reaction of the first deicerprecursor and the second deicer precursor; and distributing the deicermixture on a surface during the exothermic reaction.
 2. The method ofclaim 1, wherein distributing occurs upon completion of the exothermicreaction.
 3. The method of claim 1, wherein the mixing further includesadding a metered amount of the first deicer precursor to a meteredamount of the second deicer precursor.
 4. The method of claim 1, whereinthe first deicer precursor is an acidic solution and the second deicerprecursor is an alkaline solution.
 5. The method of claim 1, wherein thedeicer mixture is a potassium acetate solution.
 6. The method of claim1, further including transferring the deicer mixture from the vessel toa dispenser prior to distributing the deicer mixture on the surface. 7.The method of claim 1, further including adding a corrosion inhibitor tothe deicer mixture.
 8. The method of claim 1, further including stirringthe first deicer precursor and the second deicer precursor in the vesselto promote the exothermic reaction.
 9. A method of deicing a surface,comprising: receiving, at one inlet location of a vessel, a first deicerprecursor; receiving, at a plurality of inlet locations of the vessel, asecond deicer precursor; mixing the first and second deicer precursorsresulting in a deicer mixture and causing an exothermic reaction; anddistributing the deicer mixture onto a surface during the exothermicreaction.
 10. The method of claim 9, wherein distributing the deicermixture occurs upon completion of the exothermic reaction.
 11. Themethod of claim 9, further comprising transferring the deicer mixturefrom the vessel to a dispenser prior to distributing the deicer mixtureonto the surface.
 12. The method of claim 11, wherein transferringfurther includes forcing the deicer mixture to exit the vessel usingsteam generated during the exothermic reaction.
 13. The method of claim9, wherein the first deicer precursor is an acidic solution and thesecond deicer precursor is an alkaline solution.
 14. The method of claim9, wherein the deicer mixture is a potassium acetate solution.
 15. Themethod of claim 9, further including adding a corrosion inhibitor to thedeicer mixture.
 16. The method of claim 9, wherein receiving the firstdeicer precursor and the second deicer precursor includes controllingthe amount of the first and second deicer precursor.